A drivetrain in an engine may comprises a crankshaft, pistons, piston pins, and connecting rods, which are each pivotally connected to the associated piston via the piston bolt arranged in the small connecting rod eye and mounted rotatably on a crank journal of the crankshaft in the large connecting rod eye. The pistons are configured to transmit the gas forces generated by combustion to the crankshaft. The gas forces are transmitted through the pistons to the piston bolts, connecting rods, and the crankshaft. The arrangement described of piston, piston bolt, connecting rod and crankshaft transforms the oscillating motion of the piston into a rotary motion of the crankshaft. The connecting rod may move partly rotationally and partly oscillating in the direction of the cylinder bore longitudinal axis.
Various components in the drivetrain such as the crankshaft, piston, etc., may generate vibration during engine operation. The vibrations in these components may be transferred to other components in the engine as well as vehicle components, which may include camshafts, the vehicle cabin, vehicle tires, engine compartment, etc. It may be desirable to attenuate vibration generated in these components to reduce noise, vibration, and harshness (NVH) in the vehicle and engine which may negatively impact customer satisfaction as well as component longevity.
Therefore, compensation weights (e.g., counterweights) may be used in crankshafts to attenuate vibrations. However, the compensation weight may not attenuate a desired amount of vibrations due to packaging constraints. For instance, the crankcase may spatially constrict the shape and size of the counterweights. Therefore, the counterweights may be positioned outside the crankcase in an attempt to attenuate a desired amount of vibration generated in the drivetrain. However, positioning the counterweight outside of the crankcase may decrease the compactness of the engine as well as increase manufacturing costs. Furthermore, increasing the mass of the counterweight may also increase fuel consumption. For instance, the counterweights positioned external to the crankcase may have additional weight which increased losses in the drivetrain. Therefore, there may be tradeoffs between crankshaft vibration attenuation and fuel consumption in previous engines.
As such in one approach, an internal combustion engine with a cylinder and with a crank drive is provided. The internal combustion engine includes a crankshaft in which the crankshaft mounted in the crankcase has an associated crankshaft throw for the cylinder. The internal combustion engine further includes a compensation weight serving as a counterbalance for mass compensation arranged on the crankshaft on the side opposite the crankshaft throw, where the compensation weight includes an outward-facing side and a distance from a peripheral surface of the outward-facing side to a longitudinal axis of the crankshaft is not constant along the length of the peripheral surface of the outward-facing side.
Shaping the counterweight in this way enables the counterweight to be positioned within the crankcase, if desired, while attenuating a desired amount of vibration generated via the drivetrain. As a result, the compactness of the engine may be decreased if desired, NVH in the engine is reduced, and the manufacturing costs may be decreased, thereby increasing customer satisfaction.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure. Additionally, the above issues have been recognized by the inventors herein, and are not admitted to be known.
The invention is described in more detail below with reference to FIG. 1 and FIG. 2.